Solid Collector Research Articles

Studying the influence of cationized pyrolysis oil on the flotation of a bituminous coal using historical data design

ABSTRACT This investigation assessed the influence of a cationized pyrolysis oil (PO) produced by the pyrolysis of used car tires on coal flotation using an extended Historical Data (HD) design. The effect of operating factors, including pulp solid content, diesel oil, pine oil, and pyrolysis oil dosages, was examined using experimental and statistical analyses. Fourier Transform Infrared Spectroscopy (FTIR) measurement showed that PO contains hydrocarbons and their oxides (alkane, ester, or carboxylic acid). Statistical analysis using analysis of variance (ANOVA) revealed that concentrate ash content is influenced by solid content and pyrolysis oil concentration through a non-linear trend such that maximum ash removal may be obtained at the middle level of solid content and in the absence of PO. The solid content and diesel oil had a significant impact on process yield. Maximum yield was achieved at the low and middle levels of solid content and collector dosage, respectively. A comparison of individual and interaction effects of significant operating variables showed their complicated effects on process responses. Overall, the PO affected the coal flotation efficiency adversely, which can be due to the interaction between hydrophilic groups in the PO structure and the oxide nature of non-combustible materials in coal particles.

Modelling of the flotation process by Central Composite Design for obtaining superior grade feldspar

Feldspar is usually found in conjunction with titanium and iron minerals. Feldspar should be separated from other minerals by generally magnetic separation or/and flotation with high grade. However, due to the similarities in the properties, feldspars are difficult to separate from gangue minerals by flotation. In this study, the degradability of iron was investigated by mica flotation, and Central Composite Design (CCD) was used to plan and analyze the results. During the study, the effect of solid ratio, pH, collector amount and airflow on the iron content and the yield of the obtained clean feldspar were modelled. Then, estimation of the optimum conditions and verification tests were performed. The iron content was reduced to 0.14% by mica flotation. However, this reduction amount was found to be insufficient. Finally, iron content was reduced to 0.05%. Considering that the maximum iron content of the superior grade feldspar is 0.1%, it can be said that two stage flotation is successful without different processes such as magnetic separation.

MUSCULOSKELETAL DISORDER AMONG MUNICIPAL SOLID WASTE COLLECTORS: A CASE STUDY OF SUNG NOEN DISTRICT, NAKHON RATCHASIMA PROVINCE

This study aimed to investigate the prevalence of the musculoskeletal disorder among municipal solid waste collectors and factors affecting organ injuries. Data collection used a cross-sectional survey study. The population in the study consisted of 42 municipal solid waste collectors from Sung Noen district, Nakhon Ratchasima province. The research instruments were the Nordic Musculoskeletal Questionnaire (NMQ), a questionnaire on injury severity, and an ergonomic assessment checklist using the rapid entire body assessment (REBA) method. The study results found that in the past year, in 88.10% of the municipal solid waste collector, the lower back was the most prominent musculoskeletal injury, followed by the shoulders. Recently, the severity of injuries was considered mild (minor) and moderate (36.11%). The REBA revealed a modest risk. Immediate improvement needs additional analysis. The factors affecting organ injuries were types of garbage truck distance of waste collection, lifting a waste bin away from the body, lifting a waste bin above the shoulders for a long time, work-related muscle spasms, throwing the body weight on one side of the body, and hanging and swinging the body while working. The study results indicated that waste collectors must work involving repeated postures and lifting heavy objects, resulting in health problems related to chronic injury of the musculoskeletal system. Therefore, it is necessary to conduct a cause analysis to find recommendations for prevention and appropriate solutions to the problem. The novelty of the results was the types of garbage trucks causing injuries to different parts of the body. Garbage trucks included three types: small-size modified trucks, old trucks, and new trucks. Solid waste collectors using old and new trucks had more pain in their arms and legs than solid waste collectors using small-size modified trucks.

Novel Wet Electrospinning Inside a Reactive Pre-Ceramic Gel to Yield Advanced Nanofiber-Reinforced Geopolymer Composites.

Electrospinning is a versatile approach to generate nanofibers in situ. Yet, recently, wet electrospinning has been introduced as a more efficient way to deposit isolated fibers inside bulk materials. In wet electrospinning, a liquid bath is adopted, instead of a solid collector, for fiber collection. However, despite several studies focused on wet electrospinning to yield polymer composites, few studies have investigated wet electrospinning to yield ceramic composites. In this paper, we propose a novel in-situ fabrication approach for nanofiber-reinforced ceramic composites based on an enhanced wet-electrospinning method. Our method uses electrospinning to draw polymer nanofibers directly into a reactive pre-ceramic gel, which is later activated to yield advanced nanofiber-reinforced ceramic composites. We demonstrate our method by investigating wet electrospun Polyacrylonitrile and Poly(ethylene oxide) fiber-reinforced geopolymer composites, with fiber weight fractions in the range 0.1–1.0 wt%. Wet electrospinning preserves the amorphous structure of geopolymer while changing the molecular arrangement. Wet electrospinning leads to an increase in both the fraction of mesopores and the overall porosity of geopolymer composites. The indentation modulus is in the range 6.76–8.90 GPa and the fracture toughness is in the range 0.49–0.76 MPa with a clear stiffening and toughening effect observed for Poly(ethylene oxide)-reinforced geopolymer composites. This work demonstrates the viability of wet electrospinning to fabricate multifunctional nanofiber-reinforced composites.

Green bioflotation of calcite using surfactin as a collector

In this study, the collecting effect of the biosurfactant obtained from Bacillus subtilis on the flotation of calcite mineral was investigated. NMR and FT-IR analyses show that the obtained biosurfactant is similar to surfactin. It is known that surfactin is a biomolecule used in various industrial fields such as cleaning and cosmetics apart from mining. Surfactin is an amphiphilic molecule containing hydrophobic and hydrophilic parts. With this feature, the surfactin has the potential to be used as a collector in flotation. In preliminary tests, it has been observed that the surfactin floats calcite efficiently. Central Composite Design (CCD) method was used in systematic calcite bioflotation experiments. In the bioflotation test results in which the effects of solid ratio, pH and collector amount were examined, 80% calcite recovery was obtained. In order to compare the results of bioflotation and classical flotation, several calcite flotation experiments were performed with oleate under the conditions given in the literature. According to the results, the pH in bioflotation is close to the natural pH of the pulp and the bioreagent consumption is one-tenth of the oleate consumption. These data suggest that on an industrial scale, the bioreagent could be a strong competitor to oleate.

Hydrodynamic and electrical interactions in electrospinning of polymer fibers over a liquid collector

AbstractThis paper reports the morphology manipulation of electrospun polymer fibers using a rotating water collector. The hydrodynamic and electrical interactions of the employed liquid collector and electrospun fibers are investigated to reveal their effects on the fiber morphology. The experimental results show that hydrodynamic interaction is the dominant factor. Particularly, a higher flow velocity of the liquid collector produces a fiber mat with a larger area and lower density consisting of electrospun fibers with a smaller diameter and higher degree of alignment. By applying a rotation speed of 600 rpm, a fiber mat area can be increased by ~166% compared with the stationary solid collector while an area fraction is reduced to 45.2%. Furthermore, it is found that the electrical interaction only affects the area and density of the fiber mat. The higher electrical conductivity of the liquid collector leads to a smaller fiber mat area with higher fiber density. The present study offers a new paradigm for precisely manipulating the morphology of electrospun polymer fibers, thus leading to a broad range of applications.

Emerging wet electrohydrodynamic approaches for versatile bioactive 3D interfaces

There is a compelling need for delicate nanomaterial design with various intricate functions and applications. Electrohydrodynamics applies electrostatic force to overcome the surface tension of a liquid jet, shrinking the jet through intrinsic jetting instability into submicron fibers or spheres, with versatility from a huge selection of materials, feasibility of extracellular matrix structure mimicry and multi-compartmentalization for tissue engineering and drug delivery. The process typically involves the collection and drying of fibers at a solid substrate, but the introduction of a liquid phase collection by replacing the solid collector with a coagulation bath can introduce a variety of new opportunities for both chemical and physical functionalizations in one single step. The so-called wet electrohydrodynamics is an emerging technique that enables a facile, homogeneous functionalization of the intrinsic large surface area of the submicron fibers/spheres. With a thorough literature sweep, we herein highlight the three main engineering features integrated through the single step wet electrospinning process in terms of creating functional biomaterials: (i) The fabrication of 3D macrostructures, (ii) in situ chemical functionalization, and (iii) tunable nano-topography. Through an emerging technique, wet electrohydrodynamics has demonstrated a great potential in interdisciplinary research for the development of functional 3D interfaces and materials with pertinent applications in all fields where secondary structured, functional surface is desired. Among these, engineered biomaterials bridging materials science with biology have already shown particular potential.

Identifying Risk Factors of Health of Solid Waste Collectors: A Cross Sectional Study

Introduction: Increase in urbanization has resulted in exponential generation of solid waste. Exposure to various types of harmful waste is known to affect health of solid waste collectors. Hard manual labour involving frequent bending, travelling for long distance and early working hours further increase their risk of health morbidity.
 Aims and Objectives: To identify risk factors of health hazards in solid waste collectors of urban Maharashtra.
 Results: A cross-sectional study was conducted to collect data regarding clinico-social profile of solid waste collectors of Pune. Diet of all the population was found to be deficit for calorie and protein. Average female solid waste collector was anemic. More than 80% of the study population reported musculoskeletal problems such as leg and black problem which increased with increase in duration of job. Skin problems like Itching, Dryness, Hypopigmentation, Lymphadenopathy and respiratory illness were significantly more among those who worked for less than five years in this job.
 Conclusion: Frequent health checkups and proper counseling regarding health care is essential for this population to decrease burden of disease.

Factors contributing to occupational injuries among solid waste collectors: across sectional study in a municipal in Tanzania

Background: Solid waste collector plays an important role in maintaining the health and hygiene in the city. In Tanzania solid waste collectors are at high risk of occupational injuries since contaminated solid waste are collected manually often by hand with little or no protection from injuries which might contribute to increases the prevalence of occupational injuries. Objective: The study aimed to assess occupational injuries and associated factors among solid waste collectors in Ilala Manicipality Tanzania. Materials and Methods: The cross-sectional study design was carried out betwen February to July 2017 involved three hundred and fifty four (354) solid waste collectors selected randomly. Closed and open ended questionnaires used to guide interviews. Categorical data was analysed to proportions and frequences and measure of association between dependent and covariet by Chi square test and logistic regression. Results: The overall annual prevalence rate of occupational injury was 40.9%. Most respondents (90.1%) used personal protective equipment during waste collection though not adequatelly and approprietly.The most common used PPE were reported to be footware (93.14%), followed by hand gloves (76.57%). More men sustained injuries as compared to the female waste collectors and the difference is statistically significant (OR=2.22, 95% C.I=1.39–3.56 ). Working experience, alcohol consumption and cigarrete smoking noted to be sigificant factors associated with the sustainaed injuries. Conclusion: Solid waste collectors are highly affected by occupational injuries. The utilization of PPE are low and inappropriate among the workers. Working experience, Sex, and risky personal habits like cigarette smoking and consumption of alcohol were factors associated with occupational injuries among solid waste collectors. There is a need to enforce safety working procedure and use of appropriate PPE for the waste handlers in all Minicipals.

Distribution of collected target debris using the large area solid debris radiochemistry collector.

A large area solid radiochemistry collector was deployed at the National Ignition Facility (NIF) with a collection efficiency for post-shot, solid target debris of approximately 1% of the total 4π solid angle. The collector consisted of a 20-cm diameter vanadium foil surrounded by an aluminum side-enclosure and was fielded 50 cm from the NIF target. The collector was used on two NIF neutron yield shots, both of which had a monolayer of 238U embedded in the capsule ablator 10 μm from the inner surface. Fission and activation products produced in the 238U were collected, and subsequent analyses via gamma spectroscopy indicated that the distribution of fission products was not uniform, with peak and valley fission products preferentially collected on the vanadium and low- and high-mass fission products primarily located on the aluminum side-enclosure. The results from these shots will be used to design future nuclear data experiments at NIF.

Recovery of coal values from the refuse pond coal slurry using flotation

ABSTRACTThe objective of the present investigation is to explore the possibility of recovery of coal values from the tailing dump, so as to recover the coal values from the discarded product for sustainable development and optimum utilization of coal reserves. The influence of two important variables which commonly fluctuate in the operating plants, such as feed solid concentrations and collector dosage, has been varied and analyzed to study their influence on flotation performance. Among the variables studied, the pulp density of 8% of feed solid concentration was found to be most suitable level. A collector dosage of 0.105 kg/ton of coal gave the best result in term of ash reduction.

Effects of operating parameters on time-dependent ash entrainment behaviour of a sample coal flotation

It is well-known that entrainment of particles into the froth is a key factor in the selectivity and performance of the flotation process, especially for fine particle recovery. Since flotation is a continuous process, in this work, the effects of operating parameters on the entrainment of ash materials in a sample coal flotation is investigated from a time-sequence viewpoint. The effects of the pulp solid content, collector concentration, frother concentration, impeller speed, and particle size on the entrainment factor and water recovery at different flotation times are evaluated using a D-optimal response surface experimental design. The experimental work carried out shows that some parameters, especially particle size and pulp density, can yield completely different responses from those reported in the literature. The observed unusual behaviours can be attributed to the entrainment mechanisms and verified by the experimental results. It is also shown that the dominant entrainment mechanism can be varied by time. In addition, the statistical analyses of the experimental design show that the effects of some parameters change during time from the initial to the final stages of the flotation process. The results obtained indicate that the particle size and pulp density are the most important parameters influencing the entrainment rate and water recovery. The effects of the collector and frother concentrations are less on the entrainment and water recovery. In addition, the interaction between the solid percentage and particle size is the only significant mixed effect.

Matrix-Assisted Pulsed Laser Evaporation: A novel approach to design mesoporous carbon films

We report on a fast synthesis method of porous carbon films on solid substrates. Thin carbon micro-structures tailored by processing conditions were synthesized for the first time by Matrix-Assisted Pulsed Laser Evaporation. The procedure consists of pulsed laser irradiation of a cryogenic target composed of phloroglucinol/glyoxylic acid organic precursors dissolved in different mixtures of solvents. An excimer UV KrF* pulsed laser was employed inside a vacuum chamber for material expulsion from the target and immobilization on a solid facing collector. By modifying laser energy or target solvents, thin polymeric coatings of hundreds of nanometers with various cross-linking degrees were obtained at room temperature in 10 min only. No drying or thermo-polymerization step is required even for high boiling point solvents such as dymethyl sulfoxide (DMSO). After thermal treatment, mesoporous carbon films exhibiting diverse nano-morphologies and surface areas up to 705 m2 g−1 determined by Kr adsorption were then directly obtained onto various collectors. Processing and assembling mechanisms of phenolic resins were investigated and two competing mechanisms, e.g., target absorption of laser wavelength and subsequent molecules transfer/interactions are accounted for the growth of high quality films as highlighted by several techniques.

Effect of reflection losses on stationary dielectric-filled nonimaging concentrators

The effect of Fresnel reflection and total internal reflection (TIR) losses on the performance parameters in refractive solar concentrators has often been downplayed because most refractive solar concentrators are traditionally the imaging type, yielding a line or point image on the absorber surface when solely interacted with paraxial etendue ensured by solar tracking. Whereas, with refractive-type nonimaging solar concentrators that achieve two-dimensional (rectangular strip) focus or three-dimensional (circular or elliptical) focus through interaction with both paraxial and nonparaxial etendue within the acceptance angle, the Fresnel reflection and TIR losses are significant as they will affect the performance parameters and, thereby, energy collection. A raytracing analysis has been carried out to illustrate the effects of Fresnel reflection and TIR losses on four different types of stationary dielectric-filled nonimaging concentrators, namely V-trough, compound parabolic concentrator, compound elliptical concentrator, and compound hyperbolic concentrator. The refractive index (RI) of a dielectric fill material determines the acceptance angle of a solid nonimaging collector. Larger refractive indices yield larger acceptance angles and, thereby, larger energy collection. However, they also increase the Fresnel reflection losses. This paper also assesses the relative benefit of increasing RI from an energy collection standpoint.

Stable Lithium Metal Anodes for Rechargeable Lithium Metal Batteries

Li metal is an ideal anode material for next-generation energy storage devices due to its extremely high theoretical specific capacity and the lowest negative electrochemical potential [1,2]. However, uncontrolled Li dendrite growth and the side reaction between Li metal and electrolytes have prevented its practical application in rechargeable Li metal batteries. In our contributions, artificial solid electrolyte interphase (SEI) layer and 3D current collector have been developed to address these issues [3,4]. In this presentation, we will introduce an artificial Li3PO4 SEI layer [3] fabricated by in situ reaction of polyphosphoric acid (PPA) with Li metal and its native film (Li2CO3, LiOH, and Li2O). The partial dissolution of the Li native film and formation of the SEI layer lead to a porous structure of the Li surface, thereby promoting Li dendrite formation and growth. In the ingenious design, the native film of Li metal is replaced by the stable and uniform Li3PO4 SEI layer. The artificial Li3PO4 SEI layer with thickness of 50 nm exhibits a smooth surface and a high Young’s modulus (10-11 GPa). Furthermore, the artificial Li3PO4 SEI layer is demonstrated to be stable in the electrolyte and during cycling in a Li|LiFePO4 battery system. The Li-conducting Li3PO4SEI layer can achieve uniform Li deposition, and reduce the side reaction between the Li metal and the electrolyte. Thus, the artificial SEI strategy we described is a promising route to tackle the intrinsic problems of Li metal anodes and other metal based anodes. Furthermore, we will show that Li metal anode can be accommodated in the reserved pores of the 3D current collector [4] with a submicron skeleton and high surface area, thereby suppressing the Li dendrite growth and solving the associated problems of Li metal anodes. Because of the high electroactive area of the submicron 3D structure, the 3D current collector can improve the Li plating/stripping efficiency and reduce the resistance of the Li metal anode. The utilization of the 3D architecture to accommodate the Li metal anode will highlight the importance of rational design of current collectors and reveal a new avenue for developing Li metal anodes with a long lifespan. References Y.-X. Yin, S. Xin, Y.-G. Guo, L.-J. Wan, Angew. Chem. Int. Ed. 2013, 52, 13186.W. Xu, J. L. Wang, F. Ding, X. L. Chen, E. Nasybutin, Y. H. Zhang, J. G. Zhang, Energ. Environ. Sci. 2014, 7, 513.N.-W. Li, Y.-X. Yin, C.-P. Yang, Y.-G. Guo, Adv. Mater. 2015, DOI: 10.1002/adma.201504526.C.-P. Yang, Y.-X. Yin, S.-F. Zhang, N.-W. Li, Y.-G. Guo, Nat. Commun. 2015, 6, 8058

Novel application of talc nanoparticles as collector in flotation

The objective of this work is to study the application of natural hydrophobic talc nanoparticle as a new class of solid flotation collector.

Integrated solid/nanoporous copper/oxide hybrid bulk electrodes for high-performance lithium-ion batteries.

Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100 mA h g−1 for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications.

Injuries among solid waste collectors in the private versus public sectors

Solid waste collection is among the occupations with the highest risk for injuries and illnesses. Solid waste collector injuries were characterized in terms of injury risk and employment industry sector (public versus private) using Kentucky workers' compensation first reports of injury and claims data. When compared to 35-44-year-old workers, solid waste collectors who were under 35 years of age were less likely to have a workers' compensation first report of injury or claim that resulted in awarded benefits. The probability that a workers' compensation first report of injury or claim would result in an awarded benefit was higher if the worker was employed as a solid waste collector in the private sector compared to the public sector, or was injured due to a motor vehicle-related injury or a push-or-pull type of injury. A better understanding of the differences in the contributing factors for an injury that results in a first report of injury or claim with awarded benefits (e.g., job activities, new and refresher worker safety training, type of equipment used, differences in collection vehicle automation, and differential reporting of injuries on the job) between the public and private sectors is necessary to target injury prevention strategies in this high-risk occupation.

Exact and approximate expressions for resistance coefficients of a colloidal sphere approaching a solid surface at intermediate Reynolds numbers

A mathematical model has been developed to describe the force of liquid flow acting on a colloidal spherical particle as it approaches a solid surface at intermediate-Reynolds-number-flow regime. The model has incorporated bispherical coordinates to determine a stream function for the flow disturbed by the sphere. The stream function was then used to derive the flow force on the particle as a function of the inter-surface separation distance. The force equation was related to the modified Stokes equation to obtain an exact analytical expression for the correction factor to the Stokes law. Finally, a rational approximation is presented, which is in good agreement with the exact numerical result, and can be readily applied to more general particle–surface interactions involving short-range hydrodynamics associated with colloidal particles in the near vicinity of a large solid collector surface at intermediate Reynolds number of the supporting flow.

Physicochemical Characterization of Casein Phosphopeptide-Amorphous Calcium Phosphate Nanocomplexes

Milk caseins stabilize calcium and phosphate ions and make them available to the neonate. Tryptic digestion of the caseins yields phosphopeptides from their polar N-terminal regions that contain clusters of phosphorylated seryl residues. These phosphoseryl clusters have been hypothesized to be responsible for the interaction between the caseins and calcium phosphate that lead to the formation of casein micelles. The casein phosphopeptides stabilize calcium and phosphate ions through the formation of complexes. The calcium phosphate in these complexes is biologically available for intestinal absorption and remineralization of subsurface lesions in tooth enamel. We have studied the structure of the complexes formed by the casein phosphopeptides with calcium phosphate using a range of physicochemical techniques including x-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and equilibrium binding analyses. The amorphous nature of the calcium phosphate phase was confirmed by two independent methods: x-ray powder diffraction and selected area diffraction. In solution, the ion activity product of a basic amorphous calcium phosphate phase was the only ion product that was a function of bound phosphate independent of pH, consistent with basic amorphous calcium phosphate being the phase stabilized by the casein phosphopeptides. Detailed investigations of calcium and calcium phosphate binding using a library of synthetic homologues and analogues of the casein phosphopeptides have revealed that although the fully phosphorylated seryl-cluster motif is pivotal for the interaction with calcium and phosphate, other factors are also important. In particular, calcium binding and calcium phosphate stabilization by the peptides was influenced by peptide net charge, length, and sequence.